$ sudo apt-get install digikam
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
digikam : Depends: kdepim-runtime but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

Trying to upgrade and reinstall digikam…

sudo apt-get upgrade
[...]
sudo apt-get install digikam

with no luck. apt-get is not able to resolve the unmet dependencies. In this situations, it’s better to use aptitude instead of apt-get: